Carburetor



y 17, 1932- y s. M. BICKNELL 5 CARBURETOR Filed Nov. 18', 1950 5Sheets-Sheet 1 61% E/(K/VELL lNVENTOR ATTORNEY May 17,1932; M. BICKNELL1,853,615

' CARBURETOR Filed Nov. 18, 1950 5 Sheets-Sheet 2 PUMP our/.51-

' a Mr E/aZ/ue-LL INVENTOR ATTORNEY y 17, 1932- ca. M/BICKNELL 1,858,615

' CARBUREI'OR Filed Nov. 18. 1930' 5 Sheets-Sheet 3 &/4. fi/CK/VELLINVENTOR ATTORNEY May 17, 1932. v a. M. BICKNELL; 1,858,615

' CARBURETOR Filed Nqv. 1a. 1950 s Shaets-Sheet 4 &M awe/v54;

INVENTOR I ATTORNEY y 1932. a. M. BICKNELL 1,858,615

CKRBURETOR Filed Nov. 18. 1950 s Sheets-Sheet 5 @M fi/CK/VELL INVENTORATTORNEY Patented May 17, 1932 UNITED STATES PATENT OFFICE GEORGE M.-3103111211., or sun LOUIS, mssounr, ASSIGNOR 'ro canrnn 'cARBUnE'roRCORPORATION, or sr. LOUIS, MISSOURI, A CORPORATION or DELAWARECARBURETOIB Application flledN'ovember 18, 1930. Serial No. 496,398.

It will be understood that the invention .is susceptible of manymodifications, and, accordingly, I do not wish to be limited in myprotection, except as set forth in the accompanying claims.

This invention relates to carburetors for internal combustion engines.In previous devices of this type considerable difficulty has beenexperienced in providing a carburetor having sufficient capacity foroperation of the engines under maximum power conditions and having, atthe same time, the ability to efficiently vaporize the fuel for low andintermediate power requirements.

It is an object of this invention to provide a carburetor for internalcombustion engines capable of efiiciently vaporizing fuel at widelyvarying rates of flow, and which will not present any great resistanceto the flow of air and fuel mixture to the engine.

It is a" further object of this invention to provide a carburetor of theabove described type capable of maintaining a substantially constantfuel mixture ratio at different rates of operation.

A furth er object of the invention is to provide a carburetor havingmeans for cooling the fuel in the float'chamber thereof.

Other objects will appear from the follow.- ing specification andaccompanying draw ings, referring to which: I

Figure 1 shows a side elevation of a carburetor constructed according toone embodiment of my invention, with parts broken away for betterillustration of others.

Figure 2 is a plan View of the carburetor shown in Figure 1.

Figure 3 shows a longitudinal sectional view of the carburetor shown inFigures 1 and 2, the section being taken along the line' 33 of Figure 2.

Figure 4 is alongitudinal sectional view of the carburetor shown in'Figures 1 to 3, the section being taken along thebroken line 4.4 ofFigure 2.

Figure 5 is a longitudinal sectional view of the carburetor shown inFigures 1 to 4 taken along the line 5-5 of Figure 2, parts being shownin section and parts being broken away for better illustration ofothers.

through the port 16. j V

The reference numeral 1 indicates a casting forming the main body memberof the carburetor." This casting has a flange 2 formed on its lower endfor attachment to the intake manifold of an internal combustion engine.An upper body member 3 is attached-to the member 1 by any suitablemeans, suchasscrews 4. An air inlet 5 is formed in the upper body memberand registers with an air chamber 6 which forms the upper end of the.main air passageway through the lower body member 1.

A venturi 7 is fitted into the air chamber 6 and extends" downwardlyinto a bore 8 which forms the mixing chamber of the carburetor. It willbe understood that the bore 6 is slightly larger in diameter than thebore 8, and that the two portions are joined by a shoulder or taperedportion 9 to provide means for locating the venturi 7 with respect tothe lengthof the carburetor;

The lower end of the bore 8 is controlled by a throttle valve 69 mountedon a shaft 10 which isjournaled inthe casting las shown.

A suitable operating lever 11 is attached to the shaft 10 for operationbyany suitable means.

An air inlet valve 12 is mounted on a shaft 13 in the upper body member3, and a suitable operating lever 14 isattached in a conventionalmanner. A stop 15 is formed inte= gral with the casting 3 and may beprovided with an adjustment, if desired.

One or more openings 16 are formed in the upper body member 3 tocommunicate with the atmosphere, and these openingsare: controlled by aspring member 17 which is attached to the inner wall of the air inlet 5by any suitable means, such as a screw or rivet 18. Itwill be understoodthat the member 17 acts as a valve which may be openedby suction topermit the admission of air ioo power, the valve 17 will be unseated andair may flow in through the port 16. Obviously,

the tension required in the spring 17 will vary with differentinstallations, but, as an illustration, the valve 17 should ordinarilyremain closed at speeds below one hundred revolutions per minute ofthemotor, and it should begin to open at. speeds in excess of that figure.

In this installation, three venturis are provided, the largest venturi 7fitting the outer wall of the carburetor as shown. The second venturi 19terminates at the throat or at the most restricted portion of theventuri 7, and the third venturi 2O terminates at the throat of the mostrestricted portion of the venturi 19.

To prevent eddy currents being formed in the venturis, I provide one ormore vanes or straighteners 21 which extend parallel to the lines offlow and which are preferably made thicker at the inlet end than at theend adj acent the outlet of the carburetor. These I vanes are mainly forthe purpose of preventing the rotation of the air currents in thecarburetor, or checking any rotation which may have been set up in theinlet, but they are also highly useful as devices for locating theventuris with respect to each other. It will be understood that wheremany thousands of carburetors are to be produced, it is essential thatthe air flow characteristics in each venturis and the vanes as a singledie casting, I am able to secure absolute uniformity so that there is noneed of separately adjusting the venturis in each carburetor.

A fuel bowl 22 is cast integrally with the lower body member 1 and aconventional float mechanism is located in this bowl for maintaining thefuel at a constant level substantially as indicated by the line AA Thefuel is supplied to the bowl by any suitable means which, being entirelyconventional, is not shown.

A cover 23 is provided for the bowl, and this cover forms an air tightseal so that the pressure conditions in the bowl may be controlled by apair of vents 24. and 25. The

vent 25 is connected to the inside of the air chamber, and the vent 24is connected to the atmosphere, thereby giving a flow of air in throughthe vent 24 and out through the vent 25. This flow of air through thefuel bowl cools the fuel by carrying ofi vapors into the mixingcon'duit.

'gljAn economlzlngaction 1s also obtained in' this construction byreason of the fact that the pressure in the fuel bowl is caused to varyinversely with the rate of flow through .the air chamber. It will beunderstood that provision of the vent 25 also helps to correctdiificulties caused by the variation in the resistance to flow throughthe air cleaner which is'normally attached to the flange 26 at the airinlet of the carburetor.

A main fuel nozzle 27 is mounted at an angle so that it will dischargeagainst the direction of air flow, thereby serving as a cor rection toassist in obtaining a substantially constant fuel mixture ratio. Thefuel issupplied to the nozzle 27 through a metering jet 28 mounted inthe lower part of the float chamber, as indicated, and the constrictionof the jet is controlled by a stepped metering rod 29 operated by thethrottle through crank 30, link 31, rock shaft 32, and crank 33.

It will be understood that a smaller step of the metering rod is broughtin juxtaposition to the restricted orifice when the throttle is inwideopen position.

The metering rod 29 enters the float chamber through an opening 7 Owhich provides a substantial amount of clearance, so that the rockingmotion of the arm 33 maybe provided for. In order to keep dust fromentering the carburetor bowl,'a fiat disk 71 is located in a counterboreat the upper end of the opening 70. The flat disk is larger in diameterthan opening and is slidably mounted on the shaft 29. The disk 71 isheld in place by a washer 72 or other suitable means.

The fuel is conveyed from the restricted orifice in the jet member 28through a cross bore 34 into a vertical bore 35 and from this bore thefuel flows through a cross bore 36 into thenozzle chamber and on upthrough the nozzle 27 through which it is discharged into the venturi20. The fuel comes out of this nozzle with some velocity andisdischarged into the most. rapidly moving portion of the air stream as itpasses through the venturi 20.

The wallsof this venturi serve as baflies to straighten out the flow; ofthe fuel. thereby preventing it from striking the walls of the airchamber or the conduit 8 until after it has been vaporized by additionalair entering the venturis '19 and 7. I consider this an importantfeature of the invention, for tests have shown that when liquid fuel isper mitted to strike the outer wall of the mixing conduit, it is likelyto be carried along in liq uid form by the air stream in such a way thatvaporization and distribution are not eficiently accomplished.

By the above arrangement, I am enabled to avoid the necessity for mixingair with the fuel in the fuel passageways and nozzles which would causethe delivery of the fuel in slugs and generally ineficient operation ofthe carburetor, particularly at low speeds.

Low speed operation of the carburetor is provided for as'follows:

The conduit 37 is concentrically mounted in the. bore 35 and is closedat its lower end,

except for a metering orifice 38. A cross bore 39 leads transversely tothe upper end of a vertical bore 40. This vertical bore extendsdownwardly to the port 41 which is formed adjacent the edge of thethrottle 9 on the side 10 which opens toward the inlet of thecarburetor. The construction andoperation of this idle port are wellknown, being previously covered in Patent No. 1,207,134 to W. 0. Carter.

The port 41 being below the fuel level in the chamber 22, an' air bleed42 is provided at a point above the fuel level for admitting air to thecross bore 39 to break the siphon and prevent the drainage of thecarburetor-when it is not in operation. An adjusting screw 43frictionally held in position by a spring 44 is provided for controllingthe admission of air at 42, so that the richness or leanness of the idlemay be adjusted.

An accelerating pump 45 is provided for delivering an increased chargeof fuel to the carburetor upon acceleration. The pump is provided withan inlet check valve 46 receiving fuel from the float bowl through the 3bore 47, and the outlet side of the check valve is connected to the pumpthrough the passage 48. The check valve 46 is threaded into a bore 49,and the outlet check valve of the accelerating pump is also threadedinto.

35 the same bore, the connection 48 being located between the twovalves.

The pump discharges into the mixing conduit through nozzle 51 which isfitted to :1

bore 52 which intersects the bore 49 on the 4.0 outlet side of the checkvalve 50. The bore 52 is plugged at 53, as indicated. The passage 48connects with the lower end of the cylinder 54 in which a piston 55 isreciprocally mounted. This piston is operated from t5 the throttlethrough link '31, rock shaft 32,

crank 56, and connecting rod 57. The nozzle 51 discharges between theventuris 19 and 7, so that the stream from the pump will hev vaporizedby the rapidly flowing air stream. The operation of the device is asfollows: The carburetor is attached to the intake manifold of an engine,and fuel is supplied to the float chamber 22 by any suitable means.Assuming that the engine is to be started 55 cold, the choke valve 12 isclosed for starting purposes and the throttle valve 69 is preferablyslightly open. It will be understood that linkage maybe provided forcausing the throttle to be slightly open when the choke 69 valve isclosed, but said linkage is not a part of this invention and need not befurther described. v

, Upon operation of the engine at cranking speeds, say, fiftyrevolutions per minute, a

strong suction acts on the nozzle 27, causing .a very rich fuel mixtureto be supplied to the the port 16 to supply the requirements of theengine and to prevent the engine being stalled by too rich a mixture,which would probably occur if all the suction caused by the engineoperating under its own power were permitted to act on the nozzle 27.After the engine is started, the valve 12 is gradually .opened, and thefree admission of air to the air inlet 5 is permitted.

Assuming that the throttle 69 is in open position, air flows through theve11turis.20, 19, and 7, and the most rapidly moving part of the airstream flows through the venturi 20. The speed of this rapidly movingair being increased by the restriction at the throat of the venturi 20,a-strong suction on the end of the nozzle 27 is caused, serving to drawfuel out of that nozzle in proportion to the speed of the air stream atlow speeds, and

athigh speeds the normal tendency of the fuel nozzle to over richness isovercome in two ways. First, the increasing impact of the air againstthe fuel issuing from the nozzle and the partial reversal Of the flow offuel which is caused to occur in the venturi 2O partially corrects thenormal tendency of this nozzle to increase the richness of the mixtureas a whole at high speeds. The tendency to increase richness at highspeeds is further counteracted by the fact that the flow ratios betweenth'eventuris 20 and 19 and 7 tend to change, as the speed increases, infavor of the larger venturis. 1

, In modern carburetors, the high capacity which is so greatly desirednecessarily involves comparatively large venturis and air passagewaysand correspondingly low suctions available to draw fuel from the nozzleduring low speed operation with wide open throttle. With thisconstruction, the difficulty of getting enough fuel at low speeds whenthe throttle is open is overcome, to a great extent, by the fact thatthe impact of on account of the economizing action of the impact of theair stream against the fuel which is discharged from the nozzle 27. It

will be understood that it is not only the impact of'the air strikingagainst the fuelwhich retards it, .but also the suction is lowered bythe fact that the velocity-of the air is slightly reduced by'the inertiaof the fuel which it must overcome. I

During low speed closed throttle opera- 1. In a carburetor, meansforming a mixing conduit, a venturi in said conduit, a second venturidischarging substantially at the throat of said first named venturi, aconstant level fuel chamber, a nozzle receiving fuel from saidconstantdevel chamber, said nozzle discharging at an angle against theair stream at an acute angle to the path of flow of air in the saidsecond venturi.

2. In a carburetor,means forming a mixing conduit, a venturi insaid-conduit, an air inlet for said venturi, a fuel nozzle discharginginto said venturi at an angle against the flow'of air entering saidinlet, a throttle valve in said mixing conduit, a low speed conduitdischarging adjacent the edge ofsaid throttle valve, and means forreducing the flow of fuel through said nozzle according to the degreeof. suction applied to said low speed conduit. I

3. In a carburetor, means forming a mixing conduit, a throttle valvecontrolling said conduit, a high speed fuelnozzle discharging intosaidconduit anterior to the throttle and at an angle against the airstream flowing through said conduit, a low speed nozzle connected todischarge fuel to said mixing 0on duit posterior to said throttle, andmeans for reducing the flow through each of said fuel conduits inaccordance with the amount of fuel being discharged through the other ofsaid fuel conduits.

4. In a carburetor, means forming a mixin g conduit, a fuelsu-pplychamber,acalibrated passageway receiving fuel from said supplychamber, a high speed fuel conduit and alow speed fuel conduit connectedto each other and both connected to receive fuel through said calibratedpassageway, said high speed conduit discharging at an angle against theair streamin saidmixing conduit, and said lowspeed conduit discharginginto said mixing conduit posterior to said high speed conduit.

5. In a carburetor, means forming a mixing conduit, a throttling valvecontrolling said conduit; a low speed port in the wall of said conduit,said low speed port opening into said mixing chamber, both above andbelow the throttle valve when it is in closed position, a fuel supplychamber, a restricted and calibrated passageway leading from said fueldownwardly extending conduit, each except I the last of said venturisbeing smaller than the next lower venturi and discharging near the mostrestricted portion thereof, and a fuel conduit leading from saidconstant level fuel chamber and discharging at an angle upwardly againstthe air stream at an acute angle to the path of flow of air in theuppermost and smallest of said venturis.

7. In a carburetor, means forming a mix ing conduit, a fuel nozzledischarging at an acute angle in opposite direction the air stream flowin said mixing conduit, said conduit comprising at least a pair ofconcentric Walls, and said nozzle discharging toward the inner of saidwalls, whereby the direct direct discharge of fuel against the outerwall of said conduit will be prevented.

8. In a down draft carburetor, means forming a downwardly conductingmixing conduit, a fuel chamber, means for maintaining a substantiallyconstant fuel level therein, and a fuel nozzle discharging into saidconduit, said fuel nozzle being directed upwardly against said airstream at an angle to the vertical and discharging above said level inopposition to the path of flow of air, whereby the fuel issuing fromsaid nozzle will be caused to meet the air stream flowing past theoutlet of said nozzle at a higher velocity than the absolute velocity ofthe air.

9. In a down draft carburetor, walls forming a downwardly conductingmixing conduit, a suction operated nozzle discharging upwardly againstsaid air stream at an angle acute to the path of flow thereof, andbafile means mounted in the line of discharge of said nozzle between theoutlet of the nozzle and the opposite wall of the mixing conduit,whereby unvaporized fuel discharged from said nozzle will be preventedfrom directlyimpinging on the outer wall of said conduit,

10. In at down draft carburetor, means forming a downwardly conductingmixing conduit, a main venturi in said conduit, means forming a constantlevel fuel supply cha-m-- ber, a suction operated nozzle forv conveyingfuel from said supply chamber to said mixing con-duit, said nozzle beingdirected up from said nozzle directly against the outer wall of saidconduit.

11. In a down draft carburetor, means forming a mixing conduit, saidmixing conduit vhaving an air inlet of comparatively large area, and amixture discharge outlet of. smaller area, a venturi between said inletand said outlet, a fuel nozzle discharging upwardly at an angle acute tothe path of flow of air in said mixing conduit, a throttle forcontrolling said outlet, an accelerat m pump connected to and operatedby sai throttle, said pump having a discharge nozzle mounted in a wallof said conduit and having its outlet anterior to said venturi and in apoint of comparatively low restriction and low velocity in said mixingconduit, the

flow from said fuel nozzle being reduced at high velocities by theimpact of air striking the fuel as it issues therefrom.

12. In a carburetor, means forming a constant level fuel chamber, a ventin said chamber above the fuel level therein, means forming a downwardlyconducting mixing conduit having an air inlet above the fuel level insaid chamber and a mixture outlet below said fuel level, a venturi insaid conduit, an

' upwardly conducting fuel nozzle leading from a point near the bottomof said fuel chamber and discharging, at a point above the said fuellevel and into the restricted'part of said venturi, the outlet of saidfuel conduit comprising a straight line passageway extending from apoint substantially below the fuel level, whereby air flowing downwardlythrough the mixing conduit will be caused to impact directly against thefuel in said nozzle, a flow restricting device near the inlet end ofsaid fuelconduit, a throttle .con-

40 trolling the discharge of mixture from said mixing conduit,conduitmeans connected to said fuel conduit between saidflow restrictingdevice and its outlet and having an outlet port into said mixing conduitadjacent said throttle,-at least a portion of said outlet port beingexposed to suction below said throttle said suction and the. impact ofair flowing through the mixing conduit acting in conjunction with. saidflowirestricting device to retard the discharge from said nozzle;

{In1 witness whereof I have hereunto set my ian v GEORGE M. BICKNELL;

